Strengthened Delocalized Electronic Effect in Nano-Nickel@Carbon with High Pyrrolic Nitrogen for Selective Hydrogenation of Substituted Nitrobenzene Hydrogenation

Carbon-encapsulated metal (CEM) catalysts reconfigure the active site of the catalytic reaction by shifting from the conventional metal to the surface of the carbon material. Carbon-encapsulated structure has attracted wide attention in the fields of electrochemistry, thermal catalysis and photocatalysis. Herein, a nitrogen-doped carbon-encapsulated nickel catalyst was synthesized via hydrothermal synthesis, with pyrrolic N (N_Pyr) content accounting for 48.4% of the total nitrogen species. Experiments and density functional theory calculations reveal that the five-membered pyrrole ring shares six π electrons, and its electron cloud density on the carbon surface surpasses that of benzene or pyridine ring, promoting extensive electronic interaction between N_PyrC and nickel. The interaction also extends beyond the vicinity of the doping sites and permeates throughout the entire carbon shell, thereby augmenting a greater number of potential active sites on the NC layer. This strengthened delocalized electronic effect imparts specificity in the adsorption and dissociation processes of hydrogen and p-chloronitrobenzene, leading to enhanced catalytic performance in the hydrogenation production of p-chloroaniline. The precise preparation of N_Pyr-doped CEM catalysts demonstrates its huge potential for industrial applications.